紫外光照射對聚碳酸酯溶劑質傳的影響

The effect of ultraviolet irradiation on mass transport of solvents diffusing in polycarbonate

蕭聿鈞

指導教授 ： 李三保

國立清華大學/工學院/材料科學工程學系/碩士(2013年)

摘要

我們探討波長254 nm紫外光照射後的聚碳酸酯中丙酮的質傳。在不同紫外光照射劑量的質傳實驗結果非常符合Harmon的理論模型。曲線配合的結果會得到兩個特徵參數: 擴散係數(D)和速率常數(v)。在四個不同劑量中所得到的擴散係數(D)和速率常數(v)兩者皆符合Arrhenius方程式。

由擴散係數取對數(log(D))和溫度倒數(1/T)的作圖中，我們可以得到在轉折點的地方斜率會有明顯的改變: 在低於轉折點的溫度範圍中，無論聚碳酸酯經過紫外光照射與否，斜率幾乎是一樣的。但是在高於轉折點的溫度範圍中，全部試片的實驗結果都在同一條線上，這個結果指出在此丙酮質傳實驗溫度範圍內，聚碳酸酯結構為同樣的機制。會有此現象是因為溶劑在聚碳酸酯中引發了結晶。而且，聚碳酸酯的莫耳分子量和玻璃轉換溫度兩者皆隨著紫外光照射劑量的增加而減少。所以，此實驗的結果也證明了在波長254 nm的紫外光照射時，聚碳酸酯會產生光的弗賴斯重排反應。

關鍵字

聚碳酸酯 ； 紫外光 ； 質傳

並列摘要

Acetone transport in polycarbonate without and with irradiation of 254 nm wavelength UV exposure have been investigated. The experimental mass transport with various doses are fitted with Harmon’s model. These data can be curve fitted well by the model proposed by Harmon et al. The characteristic parameters of diffusion coefficient (D) and velocity (v) satisfied the Arrhenius equation for all irradiation doses. In the figure of log (D) versus 1/T, the slope changes appreciably at the transition point (about -2℃). At the temperature range below the transition temperature, the slopes are almost the same before and after the exposures. But at the temperature range above the transition temperature, the data of four doses are overlapped. It is indicated that the structure of irradiated polycarbonate for acetone transport are similar in this ranges. These phenomena were attributed to the solvent-induced crystallization in polycarbonate. Furthermore, the molecular weight and glass transition temperature of polycarbonate decreased with increasing the ultraviolet dose. This result of experiment confirms that polycarbonate occurred photo-Fries rearrangement during ultraviolet exposure with wavelength of 254 nm irradiation.

並列關鍵字

polycarbonate ； maastransort ； ultraviolet

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